TY - JOUR
T1 - Eye position modulates retinotopic responses in early visual areas
T2 - a bias for the straight-ahead direction
AU - Strappini, Francesca
AU - Pitzalis, Sabrina
AU - Snyder, Abraham Z.
AU - McAvoy, Mark P.
AU - Sereno, Martin I.
AU - Corbetta, Maurizio
AU - Shulman, Gordon L.
N1 - Publisher Copyright:
© 2014, The Author(s).
PY - 2015/9/28
Y1 - 2015/9/28
N2 - Even though the eyes constantly change position, the location of a stimulus can be accurately represented by a population of neurons with retinotopic receptive fields modulated by eye position gain fields. Recent electrophysiological studies, however, indicate that eye position gain fields may serve an additional function since they have a non-uniform spatial distribution that increases the neural response to stimuli in the straight-ahead direction. We used functional magnetic resonance imaging and a wide-field stimulus display to determine whether gaze modulations in early human visual cortex enhance the blood-oxygenation-level dependent (BOLD) response to stimuli that are straight-ahead. Subjects viewed rotating polar angle wedge stimuli centered straight-ahead or vertically displaced by ±20° eccentricity. Gaze position did not affect the topography of polar phase-angle maps, confirming that coding was retinotopic, but did affect the amplitude of the BOLD response, consistent with a gain field. In agreement with recent electrophysiological studies, BOLD responses in V1 and V2 to a wedge stimulus at a fixed retinal locus decreased when the wedge location in head-centered coordinates was farther from the straight-ahead direction. We conclude that stimulus-evoked BOLD signals are modulated by a systematic, non-uniform distribution of eye-position gain fields.
AB - Even though the eyes constantly change position, the location of a stimulus can be accurately represented by a population of neurons with retinotopic receptive fields modulated by eye position gain fields. Recent electrophysiological studies, however, indicate that eye position gain fields may serve an additional function since they have a non-uniform spatial distribution that increases the neural response to stimuli in the straight-ahead direction. We used functional magnetic resonance imaging and a wide-field stimulus display to determine whether gaze modulations in early human visual cortex enhance the blood-oxygenation-level dependent (BOLD) response to stimuli that are straight-ahead. Subjects viewed rotating polar angle wedge stimuli centered straight-ahead or vertically displaced by ±20° eccentricity. Gaze position did not affect the topography of polar phase-angle maps, confirming that coding was retinotopic, but did affect the amplitude of the BOLD response, consistent with a gain field. In agreement with recent electrophysiological studies, BOLD responses in V1 and V2 to a wedge stimulus at a fixed retinal locus decreased when the wedge location in head-centered coordinates was farther from the straight-ahead direction. We conclude that stimulus-evoked BOLD signals are modulated by a systematic, non-uniform distribution of eye-position gain fields.
KW - Gain field
KW - Gaze
KW - Retinotopy
KW - Vertical meridian
KW - Wide-field
UR - http://www.scopus.com/inward/record.url?scp=84940582234&partnerID=8YFLogxK
U2 - 10.1007/s00429-014-0808-7
DO - 10.1007/s00429-014-0808-7
M3 - Article
C2 - 24942135
AN - SCOPUS:84940582234
SN - 1863-2653
VL - 220
SP - 2587
EP - 2601
JO - Brain Structure and Function
JF - Brain Structure and Function
IS - 5
ER -